District heating from large boiler houses. Boilers as a source of heat supply to consumers. Appointment of boiler rooms. Thermal diagram of a hot water boiler house Types of heating boilers
The gas boiler installation is the most popular in its class. Since, having connected to the gas supply line, you do not need to worry about the delivery and storage of fuel. It should be said that gas is a class of fuel that is explosive and flammable, and if used improperly, it can be released into the room. That is why it is necessary to carefully comply with all the design standards for a gas boiler house (calculations, gas supply and gas duct standards, etc.), which are indicated in SNiP in order to avoid danger.
Gas installations with a license of this class provide heating and hot water for industrial facilities, residential buildings, cottages and settlements, as well as agricultural facilities.
Advantages and disadvantages of gas equipment
The main advantages of gas boiler equipment include:
- Profitability. A gas boiler house with a license will use fuel economically, and at the same time, generate a sufficient amount of thermal energy (automatics do all the calculations). With proper circuit design, this setup is very advantageous in operation;
- Environmental friendliness of fuel. Today it is very important factor. Manufacturers are trying to produce equipment with maximum level emissions cleaning. It should also be noted that CO2 emissions when operating a device with a license of this class are minimal;
- High rate of efficiency. Gas equipment produces the highest coefficient, the rate of which reaches up to 95%. And accordingly, during operation, high-quality heating of the premises comes out;
- The equipment of a gas boiler house has smaller dimensions than in installations of another class;
- Mobility. This only applies to modular gas installations. Their design takes place at the factory, and they are produced with a license;
- For ease of use, you can install GSM control boilers (this way you can carry out all calculations and enter parameters, monitor emissions).
Designing gas boilers with an automated scheme allows you to reduce operator control.
The disadvantages of operating gas installations of this class are:
- It is necessary to carry out licensed maintenance of the boiler house before the start of the heating season, since this equipment is a source of danger and gas emissions are possible during operation;
- Connecting to the central gas pipeline (obtaining a license) is expensive and a long process (if not available);
- The operation of gas units directly depends on the calculation of the pressure in the line;
- This equipment is volatile, but this problem is fixable if uninterruptible power is provided in the circuit;
- In order to obtain a license for installation on gas (natural or liquefied), one must comply with strict licensed inspection inspection standards in accordance with SNiP.
Turnkey gas installation design
The design of gas boiler houses with a license consists in drawing up and calculating a scheme for heating, gas supply and gas ducts. To do this, you must definitely familiarize yourself with the norms of SNiP "Gas boiler houses" and take into account the characteristics when installing heating units and gas ducts.
The design of a gas boiler house should take place in a certain sequence and in accordance with the following points (norms):
- Architectural and construction schemes and drawings are carried out in accordance with the norms of SNiP. Also at this stage, the wishes of the customer (in the calculations) are taken into account.
- The calculation of the gas boiler house is carried out, that is, the amount of necessary thermal energy for heating and supply is calculated hot water. In other words, the power of the boilers that will be installed for operation, as well as their emissions.
- The location of the boiler room. This is an important point in the design of gas boilers, since all working units are located according to the standards in one room with a certain calculation. This room can be in the form of an extension or a separate building, it can be inside a heated facility, or on a roof. It all depends on the purpose of the object and its design.
- Development of schemes and plans that help gas boiler equipment to function. The class of automation and the heat supply system should be taken into account. All gas supply schemes for the boiler room must be equipped in accordance with the norms of SNiP. Do not forget that these installations are quite dangerous and proper development is very important. The development must be carried out by qualified turnkey specialists who are licensed for this.
- It is necessary to check the object for safety by conducting a special examination.
With improper, unlicensed design of gas boilers, you can incur large financial costs (fines), as well as be in danger during operation. It is better to entrust the installation of equipment of this class to companies that install turnkey gas boilers. Companies are licensed to perform these works, and this guarantees long-term operation. gas installation and compliance with all norms of SNiP.
The principle (diagram) of operation of a gas installation
The operation of equipment of this class does not include complex processes and schemes (calculations). The gas ducts of the boiler house carry out gas supply, that is, they supply fuel (natural or liquefied gas) to the burner in the boiler or boilers (if the installation has several gas units according to the license). Further, the fuel burns in the combustion chamber, as a result of which the coolant is heated. The coolant circulates in the heat exchanger.
In boiler plants with gas supply there is a distribution manifold. This structural element calculates and distributes the coolant along the established circuits (depending on the gas boiler scheme). For example, it can be heating radiators, boilers, underfloor heating, etc. The coolant gives its thermal energy and returns to the boiler in the reverse direction. Thus, circulation takes place. The distribution manifold consists of a system of equipment, thanks to which the coolant circulates, and its temperature is also controlled.
The emission of fuel combustion products (natural or liquefied gas) is made through a chimney, which must be designed according to all the characteristics of SNiP in order to prevent dangerous situation.
Installations with gas supply are controlled by automation, which minimizes operator intervention in the operation process. Automation in gas equipment has multi-level protection. That is, it stops the boilers at dangerous emergency situations, calculates all parameters and emissions, etc. Modern automated systems can notify the operator even via SMS.
Rice. oneKinds
We can distinguish the following classification of licensed gas boilers, according to the method of installation:
- Rooftop installation. At production facilities, heating equipment is often mounted on the roof;
- Transportable installation. Boilers of this type are emergency, they are produced from the factory fully equipped. They can be transported after being installed on a trailer, chassis, etc. These installations are completely safe;
- Block-modular boiler room on gas. This class of installations is mounted together with the room using special modules. It is transported by any kind of transport. And it is assembled by a turnkey manufacturer. The manufacturer also deals with permits (license);
- Built-in boiler room. Gas units are installed indoors inside the building.
Rice. 2
For licensed built-in boilers, there are certain SNiP standards that must be followed to ensure safety and prevent gas emissions. A boiler room of this class should have direct access to the street.
The design of such boiler houses with gas supply is prohibited:
- in apartment buildings, hospitals, kindergartens, schools, sanatoriums, etc.
- above and below premises where there are more than 50 people, warehouses and factories with danger A, B categories (fire hazard, explosion hazard).
LPG installations
Liquefied gas boilers have their advantages, for example, there are no problems with pressure in gas pipelines, there is no need to worry about increasing the cost of heating, and you can also set standards and limits yourself. This class of equipment is also autonomous.
But when designing and installing a liquefied gas boiler house, additional cash investments should be spent on the design (diagram). Since the design requires the installation of a special fuel tank. This is the so-called gas tank, which can have a volume of 5-50 m2. Here, additional gas ducts of the boiler room are installed, that is, those through which liquefied gas enters the boiler plant. This class of gas supply looks like a separate pipeline (gas duct). The frequency of filling the tank with liquefied gas depends on its volume, this can happen from 1 to 4 times a year.
Refueling of such equipment with liquefied gas is carried out by companies that are licensed to carry out work of this class on a turnkey basis. Their licensing also allows for technical inspection of gas ducts and gas tanks. Be sure to hire craftsmen who have permits and licenses, as these are works with a high level of danger.
The construction on liquefied gas is no more different from that running on natural gas. This class of equipment also includes radiators, valves, pumps, valves, automation, etc.
A gas tank with liquefied fuel can be installed in 2 versions (diagrams):
- Over the ground;
- Underground.
The design of both options should be carried out subject to certain conditions and calculations, which, among other things, are indicated in SNiP. The tank for liquefied fuel, which is located above the ground, must necessarily be enclosed by a fence (from 1.6 m). The fence should be installed at a distance of 1 meter from the tank around the entire perimeter. This is necessary for better air circulation during operation.
There are also other standards for the design and location of a ground gas tank (to avoid danger) - this is the calculation of the distance from different objects:
- At least 20 meters from residential buildings;
- At least 10 meters from roads;
- Not less than 5 meters from all kinds of structures and communications.
As for the design of the reservoir underground, all of the above standards are reduced by 2 times. But there is a calculation of the depth of immersion of a tank with liquefied gas and a flue. These design standards must be calculated individually according to the volume of the tank and its design.
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But equipment of this class also has its drawbacks during operation, since if the quality of the gas is poor, then the boiler room will not function in the specified mode. Refilling the tank must be done by a company with all permits and licenses.
Operational safety standards
The operation of gas boilers has many advantages, but do not forget about a significant disadvantage - the danger of this equipment. This is due to the use of flammable substances and combustible substances, which represent all the danger.
So we can say that such installations are
water and water vapor, in connection with which distinguish between water and steam heating systems. Water, as a heat carrier, is used from district boiler houses, mainly equipped with hot water boilers and through network water heaters from steam boilers.
Water as a heat carrier has a number of advantages over steam. Some of these benefits are especially importance when supplying heat from the CHP. The latter include the possibility of transporting water over long distances without a significant loss of its energy potential, i.e. its temperature (the decrease in water temperature in large systems is less than 1°C per 1 km of track). The energy potential of steam - its pressure - decreases during transportation more significantly, averaging 0.1 - 0.15 MPa per 1 km of track. Thus, in water systems, the steam pressure in turbine extractions can be very low (from 0.06 to 0.2 MPa), while in steam systems it should be up to 1–1.5 MPa. Increasing the steam pressure in the turbine extractions leads to an increase in fuel consumption at the CHP and a decrease in the generation of electricity for heat consumption.
Other advantages of water as a heat carrier include the lower cost of connecting local water heating systems to heat networks, and in open systems also local hot water supply systems. The advantages of water as a heat carrier is the possibility of central (at the heat source) regulation of heat supply to consumers by changing the water temperature. When using water, ease of operation - the absence of consumers (inevitable when using steam) condensate traps and pumping units for condensate return.
On fig. 4.1 shows a schematic diagram of a hot water boiler.
Rice. 4.1 Schematic diagram of a hot water boiler: 1 - network pump; 2 - hot water boiler; 3 - circulation pump; 4 – heater of chemically purified water; 5 – raw water heater; 6 – vacuum deaerator; 7 - make-up pump; 8 – raw water pump; 9 - chemical water treatment; 10 – vapor cooler; 11 - water jet ejector; 12 - supply tank of the ejector; 13 - ejector pump.
Water-heating boiler houses are often built in newly built up areas before the commissioning of the CHP and main heating networks from the CHP to these boilers. This prepares thermal load for CHPPs, so that by the time the heating turbines are put into operation, their extractions are fully loaded. Hot water boilers are then used as peak or backup. The main characteristics of steel hot water boilers are shown in Table 4.1.
Table 4.1
5. Centralized heat supply from district boiler houses (steam).
6. District heating systems.
The complex of installations designed for the preparation, transportation and use of the heat carrier constitutes the district heating system.
Centralized heat supply systems provide consumers with heat of low and medium potential (up to 350°C), the production of which consumes about 25% of all fuel produced in the country. Heat, as you know, is one of the types of energy, therefore, when solving the main issues of energy supply of individual objects and territorial regions, heat supply should be considered together with other energy supply systems - electricity and gas supply.
The heat supply system consists of the following main elements (engineering structures): a heat source, heat networks, subscriber inputs and local heat consumption systems.
Heat sources in district heating systems are either combined heat and power plants (CHP), which produce both electricity and heat at the same time, or large boiler houses, sometimes referred to as district thermal stations. CHP-based heat supply systems are called "cogeneration".
The heat received in the source is transferred to one or another coolant (water, steam), which is transported through heating networks to the subscriber inputs of consumers. To transfer heat over long distances (more than 100 km), heat transport systems in a chemically bound state can be used.
Depending on the organization of the movement of the heat carrier, the heat supply systems can be closed, semi-closed and open.
AT closed systems the consumer uses only part of the heat contained in the coolant, and the coolant itself, together with the remaining amount of heat, returns to the source, where it is replenished with heat again (two-pipe closed systems).
AT semi-closed systems the consumer uses both part of the heat supplied to him and part of the heat carrier itself, and the remaining quantities of heat carrier and heat are returned to the source (two-pipe open systems).
AT open systems, both the heat carrier itself and the heat contained in it are fully used by the consumer (single-pipe systems).
In district heating systems, as a heat carrier, water and water vapor, in connection with which distinguish between water and steam heating systems.
Water as a heat carrier has a number of advantages over steam. Some of these advantages are of particular importance when supplying heat from a CHP plant. The latter include the possibility of transporting water over long distances without a significant loss of its energy potential, i.e. its temperature, the decrease in water temperature in large systems is less than 1 ° C per 1 km of the path). The energy potential of steam - its pressure - decreases during transportation more significantly, averaging 0.1 - 0.15 MPa per 1 km of track. Thus, in water systems, the steam pressure in turbine extractions can be very low (from 0.06 to 0.2 MPa), while in steam systems it should be up to 1–1.5 MPa. Increasing the steam pressure in the turbine extractions leads to an increase in fuel consumption at the CHP and a decrease in the generation of electricity for heat consumption.
In addition, water systems make it possible to keep the condensate of the steam heating water clean at the CHPP without the installation of expensive and complex steam converters. In steam systems, condensate is often returned from consumers contaminated and far from completely (40-50%), which requires significant costs for its purification and preparation of additional boiler feed water.
Other advantages of water as a heat carrier include the lower cost of connecting local water heating systems to heat networks, and in open systems also local hot water supply systems. The advantages of water as a heat carrier is the possibility of central (at the heat source) regulation of heat supply to consumers by changing the water temperature. When using water, ease of operation - the absence of consumers (inevitable when using steam) condensate traps and pumping units for condensate return.
7. Local and decentralized heat supply.
For decentralized heat supply systems, steam or hot water boilers are used, installed respectively in steam and hot water boilers. The choice of the type of boilers depends on the nature of the heat consumers and the requirements for the type of heat carrier. Heat supply of residential and public buildings, as a rule, is carried out using heated water. Industrial consumers require both heated water and steam.
The production and heating boiler house provides consumers with both steam with the required parameters and hot water. Steam boilers are installed in them, which are more reliable in operation, since their tail heating surfaces are not subject to such significant corrosion by flue gases as water heating ones.
A feature of hot water boilers is the absence of steam, which limits the supply of industrial consumers, and for the degassing of make-up water, it is necessary to use vacuum deaerators, which are more difficult to operate than conventional atmospheric deaerators. However, the scheme for piping boilers in these boiler houses is much simpler than in steam ones. Due to the difficulty of preventing condensation on the tail heating surfaces from water vapor in flue gases, the risk of boiler failure due to corrosion increases.
As sources for autonomous (decentralized) and local heat supply, quarterly and group heat generating installations can be used, designed to supply heat to one or more quarters, a group of residential buildings or single apartments, public buildings. These installations are, as a rule, heating.
Local heat supply is used in residential areas with a heat demand of no more than 2.5 MW for heating and hot water supply of small groups of residential and industrial buildings remote from the city, or as a temporary source of heat supply until the main source is commissioned in newly developed areas. Boiler houses with local heat supply can be equipped with cast-iron sectional, steel welded, vertical-horizontal-cylindrical steam and hot water boilers. Especially promising are hot water boilers that have recently appeared on the market.
With a sufficiently strong wear of the existing district heating networks and the lack of necessary funding for their replacement, shorter decentralized (autonomous) heat supply networks are more promising and more economical. The transition to independent heat supply became possible after the appearance on the market of highly efficient boilers of low heat output with an efficiency of at least 90%.
In the domestic boiler industry, effective similar boilers appeared, for example, the Borisoglebsky plant. These include boilers of the Khoper type (Fig. 7.1), installed in modular transportable automated boiler rooms of the MT type /4.8/. Boiler rooms also operate in automatic mode, since the Khoper-80E boiler is equipped with electrically controlled automation (Fig. 2.4).
Fig.7.1. General view of the Khoper boiler: 1 - peephole, 2 - draft sensor, 3 - tube, 4 - boiler, 5 - automation unit, 6 - thermometer, 7 - temperature sensor, 8 - igniter, 9 - burner, 10 - thermostat, - 11 - connector, 12 - burner valve, 13 - gas pipeline, 14 - igniter valve, 15 - drain plug, 16 - igniter start, 17 - gas outlet, 18 - heating pipes, 19 - panels, 20 - door, 21 - cord with euro plug.
In Fig.7.2. the factory scheme of installation of a water heater with a heating system is given.
Fig.7.2. Scheme of installation of a water heater with a heating system: 1 - boiler, 2 - tap, 3 - deaerator, 3 - expansion tank fittings, 5 - radiator, 6 - expansion tank, 7 - water heater, 8 - safety valve, 9 - pump
The delivery set of Khoper boilers includes imported equipment: a circulation pump, a safety valve, an electromagnet, an automatic air valve, an expansion tank with fittings.
For modular boiler houses, boilers of the KVA type with a capacity of up to 2.5 MW are especially promising. They provide heat and hot water supply to several multi-storey residential buildings.
"KVA" automated hot water boiler unit, operating on natural gas of low pressure under pressurization, is designed for heating water used in heating, hot water supply and ventilation systems. The boiler unit includes a hot water boiler itself with a heat recovery unit, a block automated gas burner with an automation system that provides regulation, control, parameter control and emergency protection. It is equipped with an autonomous plumbing system with shut-off valves and safety valves, which makes it easy to combine it in the boiler room. The boiler unit has improved environmental characteristics: the content of nitrogen oxides in the combustion products is reduced in comparison with the regulatory requirements, the presence of carbon monoxide is practically close to zero.
The Flagman automated gas boiler belongs to the same type. It has two built-in finned tube heat exchangers, one of which can be connected to the heating system, the other - to the hot water supply system. Both heat exchangers can work on a joint load.
The prospect of the last two types of hot water boilers lies in the fact that they have a sufficiently reduced temperature of the exhaust gases due to the use of heat recovery units or built-in heat exchangers with finned pipes. Such boilers have an efficiency factor of 3-4% higher compared to other types of boilers that do not have heat recovery units.
Finds application and air heating. For this purpose, air heaters of the VRK-S type manufactured by Teploservis LLC, Kamensk-Shakhtinsky are used. Rostov region combined with a gaseous fuel furnace with a capacity of 0.45-1.0 MW. For hot water supply, in this case, a flowing gas water heater of the MORA-5510 type is installed. In local heat supply, boilers and boiler room equipment are selected based on the requirements for the temperature and pressure of the coolant (heated water or steam). As a heat carrier for heating and hot water supply, as a rule, water is accepted, and sometimes steam with a pressure of up to 0.17 MPa. A number of industrial consumers are provided with steam pressure up to 0.9 MPa. Thermal networks have a minimum length. The parameters of the heat carrier, as well as the thermal and hydraulic operating modes of heat networks correspond to the operating mode of local heating and hot water supply systems.
The advantages of such heat supply are the low cost of heat supply sources and heat networks; ease of installation and maintenance; fast commissioning; a variety of types of boilers with a wide range of heat output.
Decentralized consumers, which, due to the large distances from the CHPP, cannot be covered by district heating, must have a rational (efficient) heat supply that meets the modern technical level and comfort.
The scale of fuel consumption for heat supply is very large. Currently, heat supply to industrial, public and residential buildings is carried out by approximately 40 + 50% of boiler houses, which is not efficient due to their low efficiency (in boiler houses, the fuel combustion temperature is approximately 1500 °C, and heat is provided to the consumer at significantly lower temperatures (60+100 OS)).
Thus, the irrational use of fuel, when part of the heat escapes into the chimney, leads to the depletion of fuel and energy resources (FER).
An energy-saving measure is the development and implementation of decentralized heat supply systems with scattered autonomous heat sources.
Currently, the most appropriate are decentralized heat supply systems based on non-traditional heat sources such as sun, wind, water.
Non-traditional energy:
Heat supply based on heat pumps;
Heat supply based on autonomous water heat generators.
Prospects for the development of decentralized heat supply systems:
1. Decentralized heat supply systems do not require long heating mains, and therefore - large capital costs.
2. The use of decentralized heat supply systems can significantly reduce harmful emissions from fuel combustion into the atmosphere, which improves the environmental situation.
3. The use of heat pumps in decentralized heat supply systems for industrial and civil sectors allows saving fuel in the amount of 6 + 8 kg of fuel equivalent compared to boiler houses. per 1 Gcal of generated heat, which is approximately 30-:-40%.
4. Decentralized HP-based systems are successfully applied in many foreign countries(USA, Japan, Norway, Sweden, etc.). More than 30 companies are engaged in the manufacture of HP.
5. An autonomous (decentralized) heat supply system based on a centrifugal water heat generator was installed in the laboratory of the OTT of the PTS Department of MPEI.
The system operates in automatic mode, maintaining the temperature of the water in the supply line in any given range from 60 to 90 °C.
The heat transformation coefficient of the system is m=1.5-:-2, and the efficiency is about 25%.
6. Further improvement of the energy efficiency of decentralized heat supply systems requires scientific and technical research to determine the optimal operating modes.
8. Choice of heat carrier and heat supply system.
The choice of heat carrier and heat supply system is determined by technical and economic considerations and depends mainly on the type of heat source and the type of heat load. It is recommended to simplify the heating system as much as possible. The simpler the system, the cheaper it is to build and operate. Most simple solutions allows the use of a single coolant for all types of heat load.
If the heat load of the area consists only of heating, ventilation and hot water, then for district heating it is usually used two-pipe water system. In those cases when, in addition to heating, ventilation and hot water supply from the area, there is also a small technological load that requires heat of increased potential, it is rational to use three-pipe water systems for district heating. One of the supply lines of the system is used to meet the increased capacity load.
In those cases when the main heat load of the area is the technological load of increased potential, and the seasonal heat load is small, as a coolant, usually couples.
When choosing a heat supply system and coolant parameters, technical and economic indicators for all elements are taken into account: heat source, network, subscriber units. Energy-wise, water is better than steam. The use of multi-stage water heating at CHPPs makes it possible to increase the specific combined generation of electrical and thermal energy, thereby increasing fuel economy. When using steam systems, the entire heat load is usually covered by the higher pressure exhaust steam, which is why the specific combined output electrical energy decreases.
The heat received in the source is transferred to one or another coolant (water, steam), which is transported through heating networks to the subscriber inputs of consumers.
Depending on the organization of the movement of the heat carrier, the heat supply systems can be closed, semi-closed and open.
Depending on the number of heat pipelines in the heat network, water heat supply systems can be single-pipe, two-pipe, three-pipe, four-pipe and combined, if the number of pipes in the heat network does not remain constant.
In closed systems, the consumer uses only part of the heat contained in the coolant, and the coolant itself, together with the remaining amount of heat, returns to the source, where it is replenished with heat again (two-pipe closed systems). In semi-closed systems, the consumer uses both part of the heat supplied to him and part of the coolant itself, and the remaining amounts of coolant and heat are returned to the source (two-pipe open systems). In open systems, both the coolant itself and the heat contained in it are completely used by the consumer (single-pipe systems).
At subscriber inputs, heat (and in some cases the heat carrier itself) is transferred from heat networks to local heat consumption systems. At the same time, in most cases, the heat unused in local heating and ventilation systems is utilized for the preparation of hot water supply systems.
At the inputs, there is also local (subscriber) regulation of the amount and potential of heat transferred to local systems, and control over the operation of these systems is carried out.
Depending on the accepted input scheme, i.e. depending on the adopted technology for transferring heat from heating networks to local systems, settlement costs of the coolant in the heat supply system can vary by 1.5–2 times, which indicates a very significant impact of subscriber inputs on the economy of the entire heat supply system.
In centralized heat supply systems, water and steam are used as a heat carrier, and therefore, water and steam heat supply systems are distinguished.
Water as a heat carrier has a number of advantages over steam; some of these advantages are of particular importance when heat is supplied from a CHP plant. The latter include the possibility of transporting water over long distances without a significant loss of its energy potential, i.e. its temperature, the decrease in water temperature in large systems is less than 1 ° C per 1 km of the path). The energy potential of steam - its pressure - decreases more significantly during transportation, averaging 0.1 - 015 MPa per 1 km of track. Thus, in water systems, the steam pressure in turbine extractions can be very low (from 0.06 to 0.2 MPa), while in steam systems it should be up to 1–1.5 MPa. Increasing the steam pressure in the turbine extractions leads to an increase in fuel consumption at the CHP and a decrease in the generation of electricity for heat consumption.
In addition, water systems make it possible to keep the condensate of the steam heating water clean at the CHPP without the installation of expensive and complex steam converters. In steam systems, condensate is often returned from consumers contaminated and far from completely (40-50%), which requires significant costs for its purification and preparation of additional boiler feed water.
Other advantages of water as a heat carrier include: lower cost of connections to heat networks of local water heating systems, and with open systems, also local hot water supply systems; the possibility of central (at the heat source) regulation of heat supply to consumers by changing the water temperature; ease of operation - the absence of consumers inevitable with a pair of steam traps and pumping units for the return of condensate.
Steam as a coolant, in turn, has certain advantages compared to water:
a) greater versatility, consisting in the ability to meet all types of heat consumption, including technological processes;
b) lower power consumption for the movement of the coolant (the power consumption for the return of condensate in steam systems is very small compared to the cost of electricity for the movement of water in water systems);
c) the insignificance of the generated hydrostatic pressure due to the low specific density of steam compared to the density of water.
Steadily pursued in our country orientation towards more economical cogeneration systems of heat supply and these positive properties of water systems contribute to their widespread use in the housing and communal services of cities and towns. To a lesser extent, water systems are used in industry, where more than 2/3 of the total heat demand is met by steam. Since industrial heat consumption is about 2/3 of the country's total heat consumption, the share of steam in covering the total heat consumption is still very significant.
Depending on the number of heat pipelines in the heat network, water heat supply systems can be single-pipe, two-pipe, three-pipe, four-pipe and combined, if the number of pipes in the heat network does not remain constant. Simplified schematic diagrams of these systems are shown in Fig. 8.1.
The most economical single-pipe (open) systems (Fig. 8.1.a) are only advisable when the average hourly consumption of network water supplied for heating and ventilation coincides with the average hourly consumption of water consumed for hot water supply. But for most regions of our country, except for the most southern ones, the estimated consumption of network water supplied for heating and ventilation needs is greater than the consumption of water consumed for hot water supply. With such an imbalance of these costs, water not used for hot water supply has to be sent to drainage, which is very uneconomical. In this regard, the most widespread in our country are two-pipe heat supply systems: open (semi-closed) (Fig. 8.1., b) and closed (closed) (Fig. 8.1., c)
Fig.8.1. Schematic diagram of water heating systems
a-one-pipe (open), b-two-pipe open (semi-closed), c-two-pipe closed (closed), d-combined, e-three-pipe, e-four-pipe, 1-heat source, 2-heat supply pipeline, 3-subscriber input , 4 - ventilation heater, 5 - subscriber heating heat exchanger, 6 - heating device, 7 - pipelines of the local heating system, 8 - local hot water supply system, 9 - heating return pipeline, 10 - hot water heat exchanger, 11 - cold water supply, 12 - technological apparatus, 13 - hot water supply pipeline, 14 - hot water recirculation pipeline, 15 - boiler room, 16 - hot water boiler, 17 - pump.
With a significant distance of the heat source from the heat supply area (at "suburban" CHPPs), it is advisable combined systems heat supply, which is a combination of a single-pipe system and a semi-closed two-pipe system (Fig. 8.1, d). In such a system, the peak hot water boiler, which is part of the CHPP, is located directly in the heat supply area, forming an additional hot water boiler house. From the CHPP to the boiler house, only such an amount of high-temperature water is supplied through one pipe, which is necessary for hot water supply. Inside the heat-supplied area, a conventional semi-closed two-pipe system is arranged.
In the boiler room, water from the CHP plant is added to the water heated in the boiler from the return pipeline of the two-pipe system, and the total flow of water with a lower temperature than the temperature of the water coming from the CHP plant is sent to heating network district. In the future, part of this water is used in local hot water systems, and the rest is returned to the boiler room.
Three-pipe systems are used in industrial systems heat supply with a constant flow of water supplied for technological needs (Fig. 8.1, e). Such systems have two supply pipes. According to one of them, water with a constant temperature enters the technological apparatus and heat exchangers for hot water supply, according to the other, water with a variable temperature goes to the needs of heating and ventilation. Chilled water from all local systems returns to the heat source through one common pipeline.
Four-pipe systems (Fig. 8.1, e), due to the high consumption of metal, are used only in small systems in order to simplify subscriber inputs. In such systems, water for local hot water supply systems is prepared directly from the heat source (in boiler rooms) and is supplied to consumers through a special pipe, where it directly enters the local hot water supply systems. In this case, the subscribers do not have heating installations for hot water supply and the recirculating water of hot water supply systems is returned for heating to the heat source. The other two pipes in such a system are for local heating and ventilation systems.
TWO-PIPE WATER HEATING SYSTEMS
Closed and open systems. Two-pipe water systems are closed and open. These systems differ in the technology of preparing water for local hot water supply systems (Fig. 8.2). In closed systems for hot water supply, tap water is used, which is heated in surface heat exchangers with water from the heating network (Fig. 8.2, a). In open systems, water for hot water supply is taken directly from the heating network. Water is taken from the supply and return pipes of the heating network in such quantities that, after mixing, the water acquires the temperature necessary for hot water supply (Fig. 8.2, b).
Fig.8.2 . Schematic diagrams of water preparation for hot water supply at subscriber rooms in two-pipe water heating systems. a-at closed system, b - open system, 1 - supply and return pipelines of the heating network; 2 - hot water heat exchanger, 3 - cold water supply, 4 - local hot water supply system, 5 - temperature controller, 6 - mixer, 7 - check valve
In closed heat supply systems, the heat carrier itself is not consumed anywhere, but only circulates between the heat source and local heat consumption systems. This means that such systems are closed in relation to the atmosphere, which is reflected in their name. For closed systems, the equality is theoretically true, i.e. the amount of water leaving the source and coming to it is the same. In real systems, always . Part of the water is lost from the system through the leaks in it: through the stuffing boxes of pumps, compensators, fittings, etc. These water leaks from the system are small and, in good operation, do not exceed 0.5% of the volume of water in the system. However, even in such an amount, they cause some damage, since both heat and coolant are uselessly lost with them.
The practical inevitability of leaks makes it possible to exclude expansion vessels from the equipment of water heating systems, since water leaks from the system always exceed the possible increase in water volume with an increase in its temperature during the heating period. Replenishment of the system with water to compensate for leaks occurs at the heat source.
Open systems, even in the absence of leaks, are characterized by inequality. Network water, pouring out from the taps of local hot water supply systems, comes into contact with the atmosphere, i.e. such systems are open to the atmosphere. Replenishment of open systems with water usually occurs in the same way as closed systems, at the heat source, although in principle in such systems replenishment is also possible at other points in the system. The amount of make-up water in open systems is much greater than in closed ones. If in closed systems the make-up water covers only water leakage from the system, then in open systems it must also compensate for the intended water withdrawal.
The absence of surface heat exchangers of hot water supply at subscriber inputs of open heat supply systems and their replacement with cheap mixing devices is the main advantage of open systems over closed ones. The main disadvantage of open systems is the need to have at the heat source a more powerful installation than closed systems for the return of make-up water in order to avoid the appearance of corrosion and scale in heating installations and heating networks.
Along with simpler and cheaper subscriber inputs, open systems also have the following positive qualities compared to closed systems:
a) allow the use of large quantities of low-grade waste heat, which is also available at CHPPs(heat of turbine condensers), and in a number of industries, which reduces fuel consumption for the preparation of coolant;
b) provide an opportunity reduction of the calculated performance of the heat source and by averaging the heat consumption for hot water supply when installing central hot water accumulators;
in) increase service life local hot water supply systems, as they receive water from heating networks that does not contain aggressive gases and scale-forming salts;
G) reduce the diameters of cold water distribution networks (by about 16%), supplying subscribers with water for local hot water supply systems through heating pipelines;
e) let go to single-pipe systems when the water consumption for heating and hot water supply coincides .
To the disadvantages of open systems In addition to the increased costs associated with handling large amounts of make-up water, these include:
a) the possibility, with insufficiently thorough water treatment, of the appearance of color in the disassembled water, and in the case of connecting radiator heating systems to heating networks through mixing units (elevator, pumping) the possibility of contamination of the disassembled water and the appearance of an odor in it due to precipitation in the radiators and the development of special bacteria in them;
b) complication of control over the density of the system, since in open systems the amount of make-up water does not characterize the amount of water leakage from the system, as in closed systems.
The low hardness of the original tap water (1–1.5 mg·eq/l) facilitates the use of open systems, eliminating the need for expensive and complex anti-scale water treatment. It is expedient to use open systems with source waters that are very hard or aggressive with respect to corrosion, because with such waters in closed systems it is necessary to arrange water treatment at each subscriber input, which is many times more complicated and more expensive than a single treatment of make-up water at a heat source in open systems.
SINGLE PIPE WATER HEATING SYSTEMS
The diagram of the subscriber input of a single-pipe heat supply system is shown in Fig. 8.3.
Rice. 8.3. Scheme of input of a single-pipe heat supply system
Network water in an amount equal to the average hourly consumption of water in hot water supply is supplied to the input through a constant flow rate machine 1. Machine 2 redistributes the network water between the hot water mixer and the heating heat exchanger 3 and provides the desired temperature of the water mixture from the heating supply after the heat exchanger. AT at night, when there is no water intake, the water entering the hot water supply system is drained into the storage tank 6 through the backwater machine 5 (automatic “to yourself”), which ensures that local systems are filled with water. When the water intake is greater than the average, the pump 7 additionally supplies water from the tank to the hot water supply system. The circulation water of the hot water supply system is also drained into the accumulator through the back-up machine 4. To compensate for heat losses in the circulation circuit, including the accumulator tank, the machine 2 maintains the water temperature slightly higher than usually accepted for hot water systems.
STEAM HEATING SYSTEMS
Fig.8.4. Schematic diagrams of steam heating systems
a - single-pipe without condensate return; b-two-pipe with condensate return; three-pipe with condensate return; 1 - heat source; 2 – steam pipeline; 3-subscriber input; 4–ventilation heater; 5 - heat exchanger of the local heating system; 6 - heat exchanger of the local hot water supply system; 7-technological apparatus; 8-condensate trap; 9 - drainage; 10 - condensate collection tank; 11-condensate pump; 12 - check valve; 13-condensate line
Like water, steam heat supply systems are single-pipe, two-pipe and multi-pipe (Fig. 8.4)
In a single-pipe steam system (Fig. 8.4, a), steam condensate does not return from heat consumers to the source, but is used for hot water supply and technological needs or is thrown into the drain. Such systems uneconomical and are used at low steam consumption.
Two-pipe steam systems with condensate return to the heat source (Fig. 8.4, b) are most widely used in practice. Condensate from individual local heat consumption systems is collected in a common tank located at the heating point, and then pumped to the heat source. Steam condensate is a valuable product: it does not contain hardness salts and dissolved aggressive gases and allows you to save up to 15% of the heat contained in steam. Preparation of new portions of feed water for steam boilers usually requires significant costs, exceeding the cost of returning the condensate. The issue of the expediency of returning condensate to the heat source is decided in each specific case on the basis of technical and economic calculations.
Multi-pipe steam systems (Fig. 8.4, c) are used at industrial sites when receiving steam from CHPPs and in the event that if the production technology requires steam of different pressures. The cost of building separate steam pipelines for steam of different pressures turns out to be less than the cost of excessive fuel consumption at a thermal power plant when steam is released at only one, the highest pressure and its subsequent reduction for subscribers who need a pair of lower pressure. Condensate return in three-pipe systems is carried out through one common condensate pipeline. In some cases, double steam pipelines are laid even at the same steam pressure in them in order to ensure a reliable and uninterrupted supply of steam to consumers. The number of steam pipelines can be more than two, for example, when reserving the supply of steam of different pressures from the CHP or if it is advisable to supply steam from the CHP with three different pressures.
At large industrial hubs that unite several enterprises, integrated water and steam systems with steam supply for technology and water for heating and ventilation needs.
At subscriber inputs of systems, except for devices that provide heat transfer to local heat consumption systems, great importance It also has a system for collecting condensate and returning it to the heat source.
Steam arriving at the subscriber input usually falls into distribution manifold, from where it is directed directly or through a pressure reducing valve (pressure machine “after itself”) to heat-using devices.
Of great importance right choice coolant parameters. When supplying heat from boiler houses, it is rational, as a rule, to choose high coolant parameters that are acceptable according to the conditions of the technology for transporting heat through the network and using it in subscriber installations. An increase in the parameters of the coolant leads to a decrease in the diameters of the heating network and a decrease in pumping costs (for water). When heating, it is necessary to take into account the influence of the heat carrier parameters on the economics of the CHP.
The choice of a water heating system of a closed or open type depends mainly on the conditions of the CHP water supply, the quality of tap water (hardness, corrosivity, oxidizability) and the available sources of low-grade heat for hot water supply.
A prerequisite for both open and closed heating systems is ensuring stable quality of hot water at subscribers in accordance with GOST 2874-73 "Drinking water". In most cases the quality of the initial tap water determines the choice of the heat supply system (STS).
With a closed system: saturation index J> -0.5; carbonate hardness<7мг-экв/л; (Сl+SО 4) 200мг/л; перманганатная окисляемость не регламентируется.
With an open system: permanganate oxidizability O<4мг/л, индекс насыщения, карбонатная жёсткость, концентрация хлорида и сульфатов не регламентируется.
With increased oxidizability (O>4 mg/l) in stagnant zones of open heat supply systems (radiators, etc.), microbiological processes develop, the consequence of which is sulfide contamination of water. So the water taken from the heating installations for hot water supply has an unpleasant hydrogen sulfide smell.
In terms of energy performance and initial costs, modern two-pipe closed and open HV systems are on average equivalent. In terms of initial costs, open systems may have some economic advantages. if there are sources of soft water at the CHPP, which does not need water treatment and meets sanitary standards for drinking water. The network of cold water supply at subscribers is unloaded, and it requires additional supplies to the CHP. In operation, open systems are more difficult than closed ones due to the instability of the hydraulic regime of the heating network, the complication of sanitary control of the density of the system.
For long-distance transportation with a heavy EMU load, if there are sources of water near the CHPP or boiler house that meet sanitary standards, it is economically justified to use an open system of TS with one-pipe (unidirectional) transit and a two-pipe distribution network.
When transporting heat over a distance of 100-150 km or more, it is advisable to check the efficiency of using a chemothermal heat transfer system (in a chemically bound state using the example methane + water \u003d CO + 3H 2).
9. CHP equipment. Basic equipment (turbines, boilers).
The equipment of heat-preparation stations can be conditionally divided into main and auxiliary. To the main equipment of the CHP and heating and industrial boiler houses include turbines and boilers. CHPPs are classified according to the type of the prevailing heat load into heating, industrial heating and industrial. Turbines of the type T, PT, R are installed on them, respectively. XXII Congress of the CPSU (LMZ), Nevsky and Kirov plants in Leningrad, Kaluga turbine, Bryansk machine-building and Kharkov turbo-generator plants. At present, large cogeneration turbines are produced by the Ural Turbine Engine Plant named after V.I. K. E. Voroshilova (UTMZ).
The first domestic turbine with a capacity of 12.MW was created in 1931. Since 1935, all thermal power plants were built for steam parameters of turbines of 2.9 MPa and 400 ° C, and the import of heating turbines was practically stopped. Beginning in 1950, the Soviet power industry entered a period of intensive growth in the efficiency of power supply installations; due to the increase in thermal loads, the process of consolidation of their main equipment and capacities continued. In 1953-1954. In connection with the growth of oil production in the Urals, the construction of a number of oil refineries of high productivity began, for which thermal power plants with a capacity of 200-300 MW were required. For them, double-selection turbines with a capacity of 50 MW were created (in 1956 for a pressure of 9.0 MPa at the Leningrad Metal Plant and in 1957 at UTMZ for a pressure of 13.0 MPa). In just 10 years, more than 500 turbines with a pressure of 9.0 MPa were installed with a total capacity of about 9 * 10 3 MW. The unit capacity of the CHPP of a number of electrical systems has increased to 125-150 MW. As the process heat load of refineries increases, as well as with the beginning of the construction of chemical plants for the production of fertilizers, plastics and artificial fibers, which had a need for steam up to 600-800 t / h, it became necessary to resume the production of backpressure turbines. The production of such turbines for a pressure of 13.0 MPa with a capacity of 50 MW was started at LMZ in 1962. The development of housing construction in large cities has created the basis for the construction of a significant number of heating CHP plants with a capacity of 300-400 MW or more. For this purpose, the production of turbines T-50-130 with a capacity of 50 MW was started at UTMZ in 1960, and in 1962 turbines T-100-130 with a capacity of 100 MW. The fundamental difference between these types of turbines is the use in them of two-stage heating of network water due to the lower selection of steam with a pressure of 0.05-0.2 MPa and the upper 0.06-0.25 MPa. These turbines can be switched to backpressure mode ( degraded vacuum) with exhaust steam condensing in a special surface of the network bundle located in the condenser for water heating. In some CHP plants, reduced vacuum turbine condensers are used entirely as the main heaters. By 1970, the unit capacity of heating CHPPs reached 650 MW (CHP No. 20 Mosenergo), and industrial heating - 400 MW (Togliatti CHPP). The total steam supply at such stations is about 60% of the total heat output, and at some CHPPs it exceeds 1000 t/h.
A new stage in the development of cogeneration turbine construction is the development and creation of even larger turbines, which provide a further increase in the efficiency of thermal power plants and reduce the cost of their construction. Turbine T-250, capable of providing heat and electricity to a city with a population of 350 thousand people, is designed for supercritical steam parameters of 24.0 MPa, 560°C with intermediate superheating of steam at a pressure of 4.0/3.6 MPa to a temperature of 565°C . The PT-135 turbine for a pressure of 13.0 MPa has two heating extractions with independent pressure control within the range of 0.04-0.2 MPa in the lower selection and 0.05-0.25 MPa in the upper one. This turbine also provides for industrial extraction with a pressure of 1.5 ± 0.3 MPa. The R-100 backpressure turbine is designed for use at thermal power plants with a significant consumption of process steam. Approximately 650 t/h of steam at a pressure of 1.2-1.5 MPa can be released from each turbine with the possibility of increasing it at the exhaust to 2.1 MPa. To supply consumers, steam from an additional unregulated turbine extraction with a pressure of 3.0-3.5 MPa can also be used. The T-170 turbine for a steam pressure of 13.0 MPa and a temperature of 565°C without intermediate overheating, both in terms of electric power and the amount of steam taken, occupies an intermediate position between the T-100 and T-250 turbines. It is advisable to install this turbine at medium-sized urban CHPPs with a significant household load. The unit capacity of CHPP continues to grow. Currently, thermal power plants with an electric capacity of more than 1.5 million kW are already being operated, built and designed. Large urban and industrial CHPPs will require the development and creation of even more powerful units. Work has already begun on determining the profile of cogeneration turbines with a unit capacity of 400-450 MW.
In parallel with the development of turbine construction, more powerful boiler units were created. In 1931-1945. direct-flow boilers of domestic design, which produce steam with a pressure of 3.5 MPa and a temperature of 430 ° C, have received wide application in the energy sector. Currently, boiler units with a capacity of 120, 160 and 220 t/h with chamber combustion of solid fuels, as well as fuel oil and gas are produced for installation at CHPPs with turbines with a capacity of up to 50 MW with steam parameters of 9 MPa and 500-535 ° C. The designs of these boilers have been developed since the 50s by almost all the main boiler plants in the country - Taganrog, Podolsk and Barnaul. Common to such boilers is the U-shaped layout, the use of natural circulation, a rectangular open combustion chamber and a steel tubular air heater.
In 1955-1965. Along with the development of installations with parameters of 10 MPa and 540°C at the CHPP, larger turbines and boiler units with parameters of 14 MPa and 570°C were created. Of these, turbines with a capacity of 50 and 100 MW with boilers of the Taganrog Boiler Plant (TKZ) with a capacity of 420 t / h of types TP-80 - TP-86 for solid fuel and TGM-84 for gas and fuel oil are most widely used. The most powerful unit of this plant, used at CHPPs of subcritical parameters, is a unit of the TGM-96 type with a combustion chamber for burning gas and fuel oil with a capacity of 480-500 t/h.
The block layout of the boiler-turbine (T-250) for supercritical steam parameters with reheat required the creation of a once-through boiler with a steam output of about 1000 t/h. To reduce the cost of building a thermal power plant, Soviet scientists M. A. Styrtskovich and I. K. Staselyavicius for the first time in the world proposed a scheme for heating a combined heat and power plant using new hot water boilers with a heat output of up to 210 MW. The expediency of heating network water at CHPPs in the peak part of the schedule with special peak water-heating boilers was proved, refusing to use more expensive steam power boilers for these purposes. Research VTI them. F. E. Dzerzhinsky ended with the development and production of a number of standard sizes of tower oil-fired water-heating boiler units with a unit heat output of 58, 116 and 210 MW. Later, boilers of smaller capacities were developed. Unlike tower-type boilers (PTVM), boilers of the KVGM series are designed to work with artificial draft. Such boilers with a heat output of 58 and 116 MW have a U-shaped layout and are designed to operate in the main mode.
The profitability of steam turbine CHP plants for the European part of the USSR was achieved at one time with a minimum heat load of 350-580 MW. Therefore, along with the construction of thermal power plants on a large scale, the construction of industrial and heating boiler plants equipped with modern hot water and steam boilers is carried out. District thermal stations with boilers of the PTVM, KVGM types are used at loads of 35-350 MW, and steam boilers with boilers of the DKVR type and others - at loads of 3.5-47 MW. Small settlements and agricultural facilities, residential areas of individual cities are heated by small boiler houses with cast iron and steel boilers with a capacity of up to 1.1 MW.
10. CHP equipment. Auxiliary equipment (heaters, pumps, compressors, steam converters, evaporators, ROU reduction and cooling units, condensate tanks).
11. Water treatment. Water quality standards.
12. Water treatment. Clarification, softening (precipitation, cation exchange, stabilization of water hardness).
13. Water treatment. Deaeration.
14. Heat consumption. seasonal load.
15. Heat consumption. Year-round load.
16. Heat consumption. Rossander chart.
Heating and district heating systems are an important link in the energy economy and engineering equipment of cities and industrial areas. To organize the operation of these systems in large cities and industrial areas, special enterprises are being created - Thermal Networks (Heating Network). In settlements where the volume of work on the operation of heat networks is insufficient to create a special organization of the Heat Network, this work is carried out by one of the workshops of the heat supply source as an independent unit.
The main task of operation is the organization of reliable, uninterrupted supply of heat of the required parameters to thermal consumers.
For this you need:
a) coordinated operation of heat sources, heat networks and heat-consuming installations of subscribers;
b) the correct distribution of the heat carrier among consumers and heat consumption devices and accounting for the released heat;
c) careful monitoring of the equipment of heat treatment plants of heat sources and heat networks, timely identification of weak areas, their correction or replacement, systematic revision and repair of equipment, ensuring the rapid elimination and localization of accidents and failures;
d) organization of systematic monitoring of the condition of the equipment of heat-consuming installations and their mode of operation.
Constant attention should be paid to improving the equipment of the heat supply system, operating methods, increasing the productivity of the operating personnel, providing conditions for the timely heat load of the CHPP, better use of the heat carrier by the subscribers, and increasing the combined generation of electric energy.
The operating personnel of the heating network must be guided in their work by the Rules for the technical operation of power plants and networks, the Safety Rules for the maintenance of heating networks, the Instructions of the Main Technical Administration of the Ministry of Energy of the Russian Federation for the operation of thermal networks, fire safety requirements and other applicable rules, instructions and guidelines issued by the Ministry of Energy of the Russian Federation and Gosgortekhnadzor .
The field of activity of the enterprise The heating network is regulated by the boundaries of service and the balance sheet belonging of the sections of the thermal mudflow.
Such boundaries are usually, on the one hand, the shut-off outlet valves of the main on the collector of the heat source (CHP or boiler house), on the other hand, the inlet valves of the heating network at group or local thermal substations of industrial enterprises and residential microdistricts or at subscriber inputs ..
In accordance with GOST 13377-75, reliability is understood as the ability of a system to perform specified functions, while maintaining its performance within specified limits, during the required period of operation.
The reason for the violation of the reliability of the heat supply system are various accidents and failures.
An accident is understood as an accidental damage to equipment that affects the heat supply to consumers.
A failure is understood as an event consisting in a malfunction of the equipment. Thus, not every failure is an accident. An accident is a failure that affects the heat supply to consumers. With a modern, very diverse structure of the heat load provided by a unified heat supply system, heat networks should be in operation around the clock and all year round. Shutdown of them from work for carrying out repairs can be allowed only for a limited period. Under these conditions, the reliability of the heat supply system is of particular importance.
The weakest link in the heat supply system at present is water heating networks, the main reason for this is external corrosion of underground heat pipelines, primarily supply lines of water heating networks, which account for over 80% of all damage.
A significant part of the heating period, as well as during the entire non-heating period, the water temperatures in the falling line of the water heating network are usually maintained at the level of 70 -80 ° C. At this temperature, in conditions of high ambient humidity, the corrosion process is especially intense, since the thermal insulation and the surface of steel pipelines are in a wet state, and the surface temperature is quite high.
Corrosion processes are significantly slowed down when the surface of pipelines is dry. Therefore, it is advisable to systematically dry the thermal insulation of underground heat pipelines during the non-heating period by occasionally raising the temperature in the supply line of the heating network to 100 ° C and maintaining this temperature for a relatively long period (approximately 30-40 hours). External corrosion is especially intense in places where the heat-insulating structure is flooded or moistened, as well as in the anode zones of heat pipelines exposed to stray currents. Identification during operation of corrosion-hazardous sections of underground heat pipelines and elimination of corrosion sources is one of the effective methods for increasing the durability of heating networks and increasing the reliability of heat supply.
The main tasks of the operational service are to ensure reliable and uninterrupted operation of the boiler plant equipment and increase its efficiency. To accomplish these tasks, it is necessary to focus on the main issues.
These include, first of all, the correct selection, placement and constant professional development of personnel. The implementation of these measures should be based on the scientific organization of labor and contribute to a steady increase in its productivity. Boiler room personnel must clearly know and accurately comply with all the requirements of the rules for the design and safe operation of steam and hot water boilers of the Gosgortekhnadzor of the Russian Federation, as well as the rules for the technical operation of power plants and networks, safety rules for servicing thermal power equipment of power plants, safety rules in the gas industry and other official rules and instructions.
Persons at least 18 years of age who have passed a medical examination, trained according to the appropriate program and have a certificate from the qualification commission for the right to service boilers may be allowed to work independently as a boiler unit operator. Re-inspection of the buildings of these persons should be carried out periodically, at least once every 12 months, as well as when switching to another enterprise or servicing boilers of a different type, or when switching boilers from solid fuel to liquid or gaseous. When transferring personnel to service boilers operating on gaseous fuels, knowledge testing must be carried out in the manner prescribed by the "Safety Rules in the Gas Industry"
Engineering and technical workers who are directly related to the operation of boiler units are tested for knowledge of the rules of Rostekhnadzor and safety rules in the gas industry periodically, but at least once every three years.
Of great importance in the organization of operation are the preparation of technically sound plans for the operation of boiler houses and their unconditional implementation. These plans should be drawn up taking into account the introduction of new technology, mechanization and automation of production.
One of the main tasks in these plans is to reduce the cost of generated heat through a more complete use of internal reserves to reduce specific fuel consumption. heat, reducing losses of fuel, electricity and water, reducing the number of maintenance personnel through the introduction of mechanization and automation of technological processes, combining professions.
To ensure the reliable operation of the equipment of the boiler house, it is of great importance to comply with the schedules of scheduled preventive repairs, timely provision of the boiler industry with the necessary materials and spare parts, as well as improved quality of repairs and reduction of equipment downtime for repairs.
The organization of equipment operation control, the creation of a technical accounting and reporting system is an important condition for ensuring optimal operating conditions for the boiler plant. Systematic monitoring of the serviceability of operating equipment allows you to detect damage in a timely manner and eliminate them as soon as possible. In accordance with the requirements of the Gosgortekhnadzor of the Russian Federation, the boiler room personnel are obliged to systematically, within the established time limits, check the correct operation of the safety valves, blow through pressure gauges and water-indicating taps, check the serviceability of all backup feed pumps by briefly starting them. Control of the operation of the equipment also includes checking for the absence of steam or leaks in the units, fittings and flange connections, the serviceability of the steam traps (automatic steam traps), the condition (density) of the lining and the serviceability of the thermal insulation of pipelines and hot surfaces of the equipment, as well as the presence of lubrication for rotating mechanisms.
Automation is the use of a set of tools that allow production processes to be carried out without the direct participation of a person, but under his control. Automation of production processes leads to an increase in output, a reduction in cost and an improvement in product quality, reduces the number of personnel, increases the reliability and durability of machines, saves materials, improves working conditions and safety.
Automation frees a person from the need to directly control the mechanisms. In an automated production process, the role of a person is reduced to setting up, adjusting, maintaining automation equipment and monitoring their actions.
If automation facilitates the physical labor of a person, then automation aims to facilitate the mental heap in the same way. The operation of automation equipment requires high technical qualifications from the service personnel.
In terms of the level of automation, thermal power engineering occupies one of the leading places among other industries. Thermal power plants are characterized by the continuity of the processes occurring in them. At the same time, the generation of heat and electric energy at any time must correspond to the consumption (load). Almost all operations at thermal power plants are mechanized, and transient processes in them develop relatively quickly. This explains the high development of automation in the thermal power industry.
Automating parameters provides significant benefits:
provides a reduction in the number of working personnel, i.e. increase in labor productivity;
leads to a change in the nature of the work of service personnel;
increases the accuracy of maintaining the parameters of the generated steam;
increases labor safety and reliability of equipment operation;
increases the efficiency of the steam generator.
Steam generator automation includes automatic control, remote control, process protection, process control, process interlocks and alarms.
Automatic control ensures the course of continuously occurring processes in the steam generator (water supply, combustion, steam overheating, etc.)
Remote control allows on-duty personnel to start and stop the steam generator set, as well as switch and regulate its mechanisms at a distance, from the console where the control devices are concentrated.
Thermotechnical control over the operation of the steam generator and equipment is carried out using automatic indicating and recording devices. The devices conduct continuous monitoring of the processes occurring in the steam generator installation, or they are connected to the measurement object by service personnel or an information computer. Thermotechnical control devices are placed on panels, control panels, as convenient as possible for monitoring and maintenance.
Technological interlocks perform a number of operations in a predetermined sequence when starting and stopping the mechanisms of the steam generator set, as well as in cases of technological protection operation.
Interlocks exclude incorrect operations during maintenance of the steam generator set, ensure shutdown of the equipment in the required sequence in the event of an accident.
Technological alarm devices inform the personnel on duty about the state of the equipment (in operation, stopped, etc.), warn about the approach of a parameter to a dangerous value, report the occurrence of an emergency state of the steam generator and its equipment. Sound and light alarms are used.
The operation of boilers must ensure reliable and safe generation of steam of the required parameters and safe working conditions for personnel. To fulfill these requirements, operation must be carried out in strict accordance with legal regulations, rules, norms and guidelines, in particular, in accordance with the "Rules for the Design and Safe Operation of Steam Boilers" of Rostekhnadzor, "Rules for the technical safety of power plants and networks". "Rules for the technical operation of installations and heating networks", etc.
On the basis of the indicated materials, job technological instructions for equipment maintenance, repair, safety, prevention and elimination of accidents, etc. should be drawn up for each boiler plant.
Technical passports for equipment, executive, operational and technological schemes of pipelines for various purposes should be drawn up. Knowledge of the instructions, operating regime cards of the boiler and the specified materials is mandatory for personnel. The knowledge of operating personnel must be systematically tested.
The operation of the boilers is carried out according to production tasks drawn up according to plans and schedules for steam generation, fuel consumption, electricity consumption for own needs, an operational log is necessarily kept, in which the instructions of the manager and records of the on-duty personnel on the operation of the equipment are entered, as well as a repair book in which record information about the observed defects and measures to eliminate them.
Primary reporting should be kept, consisting of daily statements on the operation of the units and records of recording devices, and secondary reporting, including generalized data on boilers for a certain period. Each boiler is assigned its own number, all communications are painted in a conditional color established by GOST.
Installation of boilers indoors must comply with the rules of Rostekhnadzor. safety requirements, sanitary and technical standards, fire safety requirements.
Autonomous boilers and boiler plants. The sanitary facilities of buildings can conditionally include boiler rooms and heat generators with a thermal power of 3-20 kW to 3000 kW, which have recently been called autonomous (including roof and block - mobile), and individual apartment heat generators. They, as a rule, are intended for heat supply of a separate object (sometimes a small group of nearby objects) or an individual apartment, cottage.
Features of the design and construction of autonomous boiler houses for various types of civil facilities are different. They are regulated by the set of rules SP 41-104-2000 "Design of autonomous heat supply sources".
Autonomous boiler rooms according to their placement in space are divided into: stand-alone, attached to buildings for other purposes, built into buildings for other purposes, regardless of the location floor, roof. The thermal power of the built-in, attached and roof boiler should not exceed the heat demand of the building for which it is intended to supply heat.
In some cases, with an appropriate feasibility study, it is allowed to use a built-in, attached or roof autonomous boiler house for heat supply to several buildings, if the heat load of additional consumers does not exceed 100% of the heat load of the main building. But at the same time, the total thermal power of an autonomous boiler house should not exceed the following values: 3.0 MW - for a roof and built-in boiler house with boilers for liquid and gaseous fuels; 1.5 MW - for a built-in boiler house with solid fuel boilers. Total heat output attached boiler houses is not limited.
For industrial buildings of industrial and agricultural enterprises design and construction of attached, built-in and roof boilers is allowed. For boiler rooms attached for buildings of the specified purpose, the total thermal output of the installed boilers, the unit output of each boiler and the parameters of the coolant are not standardized.
For boiler rooms embedded in industrial buildings of industrial enterprises when using boilers with a steam pressure of up to 0.07 MPa (0.7 kgf / cm 2) and a water temperature of up to 115 ° C, the thermal power of the boilers is not standardized.
Rooftop boilers for industrial buildings of industrial enterprises it is allowed to design using boilers with a steam pressure of up to 0.07 MPa (0.7 kgf / cm 2) and a water temperature of up to 115 ° C.
For residential buildings, it is allowed to install attached and roof boiler rooms with the use of hot water boilers with water temperatures up to 115 ° C, while the thermal power of the boiler room should not be more than 3.0 MW. It is not allowed to build boiler rooms in residential multi-apartment buildings.
For public, administrative and domestic buildings it is allowed to design built-in, attached and roof boilers when using:
- - hot water boilers with water heating temperature up to 115 °С;
- - steam boilers with saturated steam pressure up to 0.07 MPa (0.7 kgf / cm 2), satisfying the condition (/- 100) Kt - saturated steam temperature at operating pressure, ° С; V- water volume of the boiler, m 3.
It is not allowed to design roof, built-in and attached boiler houses to the buildings of preschool and school institutions, to the medical buildings of hospitals and polyclinics with round-the-clock stay of patients, to the sleeping buildings of sanatoriums and recreation facilities.
The possibility of installing a rooftop boiler on buildings of any purpose above the 26.5 m mark must be agreed with the local authorities of the State Fire Service.
Thermal loads for calculation and selection of boiler room equipment must be defined for three modes:
maximum - at the design temperature of the outside air (during the coldest five-day period);
average - at an average outdoor temperature in the coldest month;
The specified calculated outdoor temperatures are accepted in accordance with SNiP 23-01-99* and SNiP 41-01-2003.
The estimated performance of the boiler house is determined by the sum of heat consumption for heating and ventilation at maximum
low mode (maximum heat loads) and heat loads on hot water supply in medium mode and design loads on technological purposes in medium mode. When determining the design capacity of the boiler house, heat consumption for the boiler house's own needs, including heating in the boiler house, should also be taken into account.
Maximum heat loads for heating (? 0P1ax, ventilation (? „ max and average heat loads for hot water supply ?) IT residential, public and industrial buildings should be taken according to the relevant projects.
Technological schemes and layout of boiler room equipment should provide: optimal mechanization and automation of technological processes, safe and convenient maintenance of equipment; the smallest length of communications; optimal conditions for the mechanization of repair work; safe operation without permanent attendants by automating the technological processes of individual boiler houses.
On fig. 1.19 shows an exemplary flow diagram of autonomous heat supply sources.
The water heated in the boiler (primary circuit) enters the heaters, where it heats the water of the secondary circuit, which enters the heating, ventilation, air conditioning and hot water systems, and returns to the boiler. In this scheme, the water circulation circuit in the boilers is hydraulically isolated from the circulation circuits of the subscriber systems, which makes it possible to protect the boilers from feeding them with low-quality water in the presence of leaks, and in some cases to completely abandon water treatment and ensure reliable boilers without scale.
Repair areas are not provided for in autonomous and roof boiler houses. Repair of equipment, fittings, control and regulation devices should be carried out by specialized organizations that have the appropriate licenses, using their lifting devices and bases.
The equipment of autonomous boiler rooms should be located in a separate room, inaccessible to unauthorized entry by unauthorized people.
For built-in and attached autonomous boiler houses, closed storage warehouses for solid or liquid fuels are provided, located outside the boiler room and the building for which it is intended to supply heat.
- -s^s
expansion tank
heat exchanger
control valve
station water treatment
Rice. 1.19. Thermal-hydraulic scheme of an autonomous (roof) boiler house
Equipment for autonomous heat supply sources. Currently, the domestic industry produces cast-iron and steel boilers designed both for burning gas, liquid boiler-furnace fuel, and for layered combustion of sorted solid fuel on grates and in a suspended (vortex, fluidized) state.
If necessary, solid fuel boilers can be converted to burn gaseous and liquid fuels by installing appropriate gas-burning devices or nozzles and automation for them on the front plate.
From small cast iron sectional boilers should be called boilers of the most common brand KCHM of various modifications. Small steel boilers produced by many machine-building enterprises of various departments, mainly as consumer goods. Compared to cast-iron boilers, they are less durable (the service life of cast-iron boilers is up to 20 years, steel boilers - 8-10 years), but they are less metal-intensive and not so labor-intensive to manufacture, and are somewhat cheaper on the market for boilers and equipment.
All-welded steel boilers are more gas-tight than cast-iron boilers. The smooth surface of steel boilers reduces their pollution from the gas side during operation, they are easier to repair and maintain. Profitability (efficiency) of steel boilers is close to that of cast iron ones.
In addition to domestic boilers, in recent years, many foreign boilers have appeared on the market of boilers and boiler auxiliary equipment, including French, German, English, Korean, Finnish, etc. All of them are of high quality workmanship, good automation and control devices, and excellent design. But their retail prices, with the same thermal characteristics, are 3-5 times higher than the price level for Russian equipment, so they are less accessible to the mass buyer.
In autonomous automated boiler houses, it is recommended to use high-efficiency boilers of full factory readiness with automated burner blocks (Fig. 1.20). As a rule, the efficiency of boilers should be at least 92%. It is expedient to supply enlarged units of equipment and pipelines that are joined at the installation site. The number of boilers in the boiler room must be at least 2.
Rice. 1.20.
in Zvenigorod
In table. 1.7, 1.8 presents the technical characteristics of heating boilers for public use by ZIOSAB.
For roof and built-in boiler rooms it is recommended to use small-sized modular boilers. The design of the boilers should ensure the convenience of technological maintenance, quick repair of individual components and assemblies.
In boiler rooms, water horizontal sectional shell-and-tube and plate water heaters should be used, switched on according to countercurrent flow patterns of heat carriers.
in steam boilers steam-water and storage heaters should be used, equipped with safety valves on the side of the heated medium, as well as air and drain devices.
Each steam-water heater must be equipped with a steam trap or overflow regulator for condensate removal, fittings with shut-off valves for air release and water drain and a safety valve provided in accordance with the requirements of PB 10-115-96 of the Gosgortekhnadzor of Russia.
Table 1.7
Main technical characteristics of heating boilers ZIOSAB for municipal purposes
Boiler name |
Heat transfer validity, |
Weight, kg |
Dimensions lxwxh, mm |
pressure |
water temperature outlet, °С |
Water resistance, kPa |
tivlenie |
|
ZIOSAB-2000 |
||||||||
ZIOSAB-1000 |
||||||||
ZIOSAB-500 |
||||||||
Stavan-250 |
||||||||
Stay-125 |
Table 1.8
Emission parameters (natural gas/LVL) of ZIOSAB boilers
The performance of water heating installations is determined by the maximum hourly heat consumption for heating, ventilation and air conditioning and the estimated heat consumption for hot water supply. The number of water heaters must be at least two for each type of load, while in the event of failure of one of them, the remaining ones must ensure the release of heat in the mode of the coldest month (for hot water supply - the maximum hourly flow rate).
In boiler rooms, it is recommended to use non-foundation pumps, the flow and pressure of which are determined by thermal-hydraulic calculation. The number of pumps in the primary circuit of the boiler room should be at least two, one of which is a backup. Double pumps are allowed. Non-foundation pumps in heat consumption systems can be installed without a reserve (reserve pumps are stored in a warehouse).
Given the small size of autonomous heat supply sources, the number of valves on pipelines should be the minimum necessary to ensure reliable and trouble-free operation. The installation sites of shut-off and control valves must have artificial lighting.
Expansion tanks must be equipped with safety valves, and on the supply pipeline at the input (immediately after the first valve) and on the return pipeline in front of control devices, pumps, water and heat meters, no more than one sump (or ferromagnetic filter) is installed.
Imported boiler units and boiler rooms must have accompanying documentation in Russian, including a technical passport, a start-up and commissioning manual and maintenance, warranty obligations, addresses of manufacturers, a supplier and a service center accredited in the Russian Federation.
In autonomous boiler rooms operating on liquid and gaseous fuels, easy-to-reset (in the event of an explosion) enclosing structures should be provided at the rate of 0.03 m 2 per 1 m 3 of the volume of the room in which the boilers are located.
Water-chemical mode of operation of an autonomous boiler house must ensure the operation of boilers, heat-using equipment and pipelines without corrosion damage and deposits of scale and sludge on internal surfaces. The water treatment technology should be selected depending on the requirements for the quality of feed and boiler water, water for heating and hot water supply systems, the quality of the source water and the quantity and quality of wastewater discharged.
For built-in and attached autonomous solid or liquid fuel boilers, a fuel storage located outside the boiler room and heated buildings should be provided, with a capacity calculated according to daily fuel consumption, based on storage conditions, not less than: solid fuel - 7 days; liquid fuel - 5 days.
The number of liquid fuel tanks is not standardized. For the storage of solid fuels, a closed unheated warehouse should be provided.
Apartment heating systems. The development of market relations in our country has brought to life apartment heating systems. Such systems have also been used in multi-apartment residential buildings, including those with built-in public facilities. So in Germany, in new construction and reconstruction of old housing stock, apartment heating systems are predominantly used, allowing residents to individually use heat generators, account for energy resources and pay suppliers for them. In the USA, such systems have been developed since the pre-war period, with payment for heat supply through automatic coin acceptors.
Apartment heat supply - providing heat to heating, ventilation and hot water supply systems for apartments in a residential building. The system consists of an individual source of heat - a heat generator, hot water pipelines with water fittings, heating pipelines with
heating devices and heat exchangers of ventilation systems.
As sources of heat for apartment heating systems, it is recommended to use individual heat generators - automated boilers of full factory readiness for various types of fuel, including natural gas, operating without permanent attendants.
For multi-apartment residential buildings and built-in public buildings, heat generators with closed (sealed) combustion chamber, with safety automatics that cut off the fuel supply when the power supply is interrupted, in the event of a malfunction of the protection circuits, when the burner flame goes out, when the coolant pressure drops below the maximum allowable value, when the maximum allowable temperature of the coolant is reached, in case of violation of smoke removal (Fig. 1.21); with coolant temperature up to 95 °С; with coolant pressure up to 1.0 MPa.
In apartments of residential buildings up to 5 floors high, it is allowed to use heat generators with an open combustion chamber for hot water supply systems (high-speed instantaneous water heaters - AGV, Fig. 4.4, see chapter 4).
Atmospheric gas burner
Flow heat exchanger
Control panel with self-diagnosis controller
Rice. 1.21. The internal structure of the boiler with atmospheric
gas burner
In apartments, heat generators with a total heat output of up to 35 kW can be installed in kitchens, corridors, non-residential premises, and in built-in public premises - in premises without permanent residence of people.
Heat generators with a total heat output of more than 35 kW should be placed in one specially designated room. The total heat output of the heat generators installed in this room should not exceed 100 kW. Schemes of parallel connection of several boilers of the same type are called cascade.
The intake of air necessary for the combustion of fuel must be carried out:
- - for heat generators with closed combustion chambers by air ducts directly outside the building;
- - for heat generators with open combustion chambers - directly from the premises in which they are installed.
It is clear that in the case of apartment heat supply in multi-storey buildings, building structures have additional requirements for the installation of chimneys for individual heat generators. Chimneys can also be individual and collective. The chimney must have a vertical direction and not have narrowings; it is forbidden to lay them through living quarters.
Heat generators of the same type (for example, with a closed combustion chamber with forced smoke removal) can be connected to a collective chimney, the heat output of which differs by no more than 30% from the heat generator with the highest heat output. No more than 8 heat generators and no more than one heat generator per floor should be connected to one collective chimney.
Emissions of combustion products should, as a rule, be carried out above the roof of the building. It is allowed, upon agreement with the bodies of the State Sanitary and Epidemiological Supervision of Russia, to emit smoke through the wall of the building, while the chimney should be taken outside the dimensions of the loggias, balconies, terraces, verandas, etc.
The ventilation system in rooms with heat generators must provide the standard air exchange rate, but not less than 1 exchange per hour.
When placing a heat generator in public premises, it is necessary to provide for the installation of a gas contamination control system with automatic shutdown of the gas supply to the heat generator when a dangerous gas concentration in the air is reached - more than 10% of the lower concentration limit of natural gas flame propagation.
Maintenance and repair of heat generators, a gas pipeline, a chimney and an air duct for outside air intake should be carried out by specialized organizations that have their own emergency dispatch service.